US Secretary of State John Kerry has urged that any moves by Beijing to establish a new air defence identification zone be "done in an open, transparent way".

"We urged our friends in China to adhere to the highest standards of notice, engagement, involvement, information sharing," Mr Kerry told reporters in Beijing after a day of meetings with top Chinese leaders, including President Xi Jinping, Premier Li Keqiang and Foreign Minister Wang Yi.

"We made clear our feelings on any unilateral announcement."

Mr Kerry's trip comes amid high tension in East Asia, with Beijing and Tokyo in dispute over a group of islands called Diaoyu in China and Senkaku in Japan.

In November, Beijing drew condemnation from Washington, Tokyo and Seoul with its move to declare an "air defence identification zone" (ADIZ), over territory in the East China Sea that is also claimed by Japan.

Beijing requires aircraft flying through its ADIZ to identify themselves and maintain communication with Chinese authorities, but the zone is not a claim of sovereignty.

Patrol boats from both China and Japan regularly shadow each other in the waters near the islands.

At the same time Beijing has been acting increasingly assertive in the South China Sea, leading to territorial disputes with the Philippines, Brunei, Malaysia, Taiwan and Vietnam.

Mr Kerry said that he hopes China and the Association of Southeast Asian Nations make "rapid strides in negotiating the code of conduct ... that would reduce tensions" on the South China Sea.

"We encourage steps by everybody, not just China, to avoid all kinds of provocation and work through the legal tools available," he said.